Staple with raised bridge portion



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United States Patent 0,

STAPLE WITH RAISED BRIDGE PORTION Herbert W. Marano, Summit, N. J.,assignor to Wilson- Jones Company, Chicago, 111., a corporation ofMassachusetts Application June 30, 1953, Serial No. 365,193

1 Claim. (Cl. 85-49) The present invention relates generally to staples,and in particular it relates to staples of thin section wire for use institching and stapling machines, and to a novel method of forming thesame.

While many diiferent forms of staples have been proposed heretofore, theart generally has settled upon a staple of inverted U-shape, having astraight connecting bridge component and a leg at each end thereofdownturned at right angles to the bridge. While this type of staple,usually provided in an elongated strip or bar having a plurality ofindividual staples detachably connected in side-by-side relationship, isgenerally satisfactory, it has many disadvantages. Particularly, underdriving stress the legs are apt to take up the pressure with resultantdeformation and jamming within the exit slide of the stapledrivingmechanism. Moreover, the bridge component, if in the least out of linewith the staple-driving blade, splits or cracks, again resulting injamming of the mechanism.

It is the main object of the present invention, therefore, to provide anew and improved staple and a new and improved method of making same.

It is a further object of the present invention to provide a new andimproved staple having the bridge section of irregular outline.

It is a further object of the present invention to provide a new andimproved staple having the bridge section thereof upwardly crowned inthe central portion thereof.

It is a still further object of the present invention to provide a newand improved method of forming a staple which comprises the steps ofcrowning upwardly the center of the wire strip, thereafter angling ashort portion of the strip on each side of the crown upwardly and awayfrom the crown, thence down-turning the ends of the strip, and finallydisposing the angled portions adjacent the crowned center at rightangles to the downturned end portions.

Other, further and more specific objects of the present invention willin part be obvious and in part specifically pointed out in the followingdescription of an illustrative embodiment of the present invention,considered with the annexed drawings, wherein:

Figure 1 is a perspective view of a number of staples in accordance withthe present invention arranged in side-by side relationship in clipform; and

Figures 2, 3, 4 and 5 are perspective views illustrating the successivesteps in the formation of the staple of the present invention.

The staple according to the present invention is indicated generally byreference numeral 10, and comprises an originally straight, elongatedstrip of thin round wire of the order of .0195" in thickness, 1.0005",and about .960 long. As seen in Figures 1 and 5, each staple includes aconnecting bridge 12 and a pair of legs 14, 14 extending downwardly frombridge 12. The lower ends 16, 16 of legs 14, 14 at the outer sidesthereof are sheared at an angle of about 60 to the horizontal, therebyto provide a pointed leading portion which will more positively enterthe material being stapled.

2,741,147 Patented Apr. 10, 1956 Bridge 12 is about .500" from side toside, or more than half the length of the wire strip. In the finishedstaple, the central portion 18 of bridge 12, to the extent of about.231", or a little less than half the length thereof, is crownedupwardly, on a radius of about .230". The degree of curvature of crown18 is exaggerated to a greater degree during the formative stepsillustrated in Figures 2, 3 and 4, and in practice the crown is curvedon a radius of about .190", but in final condition, the central portion18 is crowned on a radius substantially equal to the length of thecrowned portion.

The bridge portions 20, 20 between the crowned center 18 and the ends22, 22, are perfectly straight, and legs 14, 14 extend downwardly frombridge 12 at right angles to portions 20, 20. Legs 14, 14 are each about.230" in length, or substantially equal to the length of the crownedportion 18 and to the radius on which said center 18 is crowned. The topof the crowned portion extends .0285 :003", above the level of bridgeportions 20, 20.

The staple 10 is formed in the following manner and in the consecutivesteps listed below:

1) Initially, center portion 18, a little less than onequarter of thelength of the wire strip, is crowned upwardly, as seen in Figure 2; (2)thereafter, the straight portions 20, 20 immediately adjacent crown 18are reversely angled upwardly and away from crown 18, as illustrated inFigure 3, each portion 20 being a little more in length than half of thecrown 18; (3) thence legs 14, 14 are downturned as illustrated in Figure4.

During the fabricating steps detailed above, the wire strip is firmlyheld under tension by the forming mechanism. Upon release thereof,however, the wire will spring back to a balanced position between theelastic limit of the bent wire for each opposite direction of bendduring the forming operations. Thus, crown 18 will become shallower,flattening from the deep curve of Figures 2, 3 and 4 to the shallowcurve of Figures 1 and 5, and the crown sides pieces 20, 20 willstraighten into right-angle relationship to legs 14, 14.

About one hundred and five staples 10, when butted and cemented in theside-by-side relationships of Figure 1, will make up a clip about 2% inlength.

When a clip of ordinary staples is inserted in a stapler magazine, areasonably close fit, with little or no tolerances, is needed in orderto prevent jamming of the staples in the stapler exit, or breakage ofthe staples. A staple according to the present invention, however, mayslop-fit within the magazine, for the increased length of the bridge,due to the crowned center 18, will cause a tightening or a close fit ofthe staple legs 14, 14 in the exit channel and against the sidesthereof. Furthermore, as the stapler ram descends, the initial pointcontact of the driver blade with the top of staple crown 18 is increasedas the crown is flattened to a line contact over the entire length ofcrown 18 and bridge 12, thereby insuring driving pressure over theentire bridge length, even if the original point contact is off-center.As a result, staples according to the present invention will be moreeffectively driven than is possible with conventional staples.

Variations and departures from the specific teachings and dimensioningsdescribed hereinabove, may be possible, but it is to be appreciated thatmy invention is to be limited only by the claim hereto appended.

I claim:

A substantially U-shaped wire staple for stapling de-v vices, saidstaple comprising a bridge and legs downward 1y depending from the endsof said bridge and integrally formed therewith, said bridge including anintermediate upwardly directed arcuate crown portion, the ratio of theradius of curvature of said crown portion to the height thereof beingapproximately .230 to .0285, said crown portion extending for less thanapproximately on half the length of said bridge and eaid legs beingapproximately 1,329,268 one halfthelength of said bridge. 2,128,4432,380,786 References Cited in the file of this patent 2 522 5 UNITED,STATES PATENTS 5 10,181 Dunn Aug. 15, 1882 1,262,782 Harman, Apr. 16,1918 471,137 Whetstone Apr. 30, 1918 475,574

4 Dickelmann Jan. 27, 1920 Vcgei Aug. 30, I938 Percoco July 31, 1945Whalen Sept. 19, 1950 FOREIGN PATENTS Italy May 6, 1952 Italy Nov. 6,1952

